MEDIUM
Lower Secondary Stage 7
IMPORTANT
Earn 100

For the fluorescent light bulb shown in figure, calculate the percentage of the input energy that is transferred usefully.

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Important Questions on Energy

MEDIUM
Lower Secondary Stage 7
IMPORTANT
Cambridge Lower Secondary Science Stage 7 : Student's Book>Chapter 8 - Energy>Exercise 10>Q 4

An old-fashioned filament lamp wastes 95% of the energy supplied to it. Draw an energy transfer (Sankey) diagram for it. 

MEDIUM
Lower Secondary Stage 7
IMPORTANT
Cambridge Lower Secondary Science Stage 7 : Student's Book>Chapter 8 - Energy>Exercise 10>Q 5
A car burns fuel with an energy value of 85000 J . 68000 J of this is output from the engine as wasted as heat energy. What percentage of the chemical fuel energy used by the car that will eventually end up as thermal energy?
EASY
Lower Secondary Stage 7
IMPORTANT
Cambridge Lower Secondary Science Stage 7 : Student's Book>Chapter 8 - Energy>Exercise 12>Q 1
Explain how you could use electricity from solar panels, together with other renewable energy sources, to get the electrical energy you need at any time.
MEDIUM
Lower Secondary Stage 7
IMPORTANT
Cambridge Lower Secondary Science Stage 7 : Student's Book>Chapter 8 - Energy>Exercise 12>Q 2
Name four sources of chemical energy that can be used in thermal power stations.
EASY
Lower Secondary Stage 7
IMPORTANT
Cambridge Lower Secondary Science Stage 7 : Student's Book>Chapter 8 - Energy>Exercise 12>Q 3

Choose from the following: (electrical energy heat kinetic energy potential energy)

 In the boiler, _____ is transferred to boil water and make fast-moving steam.

EASY
Lower Secondary Stage 7
IMPORTANT
Cambridge Lower Secondary Science Stage 7 : Student's Book>Chapter 8 - Energy>Exercise 12>Q 3

Choose from the following: (electrical energy, heat, kinetic energy, potential energy)

In the turbine, the steam transfers energy to turn the blades. The turning blades have _____.

MEDIUM
Lower Secondary Stage 7
IMPORTANT
Cambridge Lower Secondary Science Stage 7 : Student's Book>Chapter 8 - Energy>Exercise 12>Q 3

Choose from the following: (electrical energy, heat, kinetic energy, potential energy)

In the cooling tower, the steam is cooled to form water that can be re-used. Thermal energy from the steam is transferred as _____ into the surroundings. 

MEDIUM
Lower Secondary Stage 7
IMPORTANT
Cambridge Lower Secondary Science Stage 7 : Student's Book>Chapter 8 - Energy>Exercise 13>Q 4
Which methods of generating electricity are renewable? List them, and explain why.